(i) Field of the Invention
The present invention relates to a polyamic acid derivative and a photosensitive resin composition using it. More specifically, it relates to a polyamic acid derivative which is easily manufactured, inhibits volume shrinkage at the time of curing, and is excellent in adhesive properties to substrates, heat stability and shelf stability; and it also relates to a photosensitive resin composition using this derivative.
(ii) Description of the Related Art
As heat-resistant photosensitive materials, photosensitive polyimides have been widely used to form insulating films and passivation films for semiconductors. Most of the photosensitive polyimides are mixtures of compounds having carbon-carbon double bonds polymerizable by light irradiation and polyimide precursors, or obtained by a combination of the precursors with aforementioned unsaturated compound by such a chemical bond such as an ester. For example, these photosensitive polyimides are known from Japanese Patent Application Laid-open Nos. (Sho) 54-145794 and (Hei) 2-144539, and Japanese Patent Publication No. (Sho) 55-41422. However, in order to practically carry out a pattern treatment, it is necessary to introduce a large amount, e.g., 50% or more of a compound having a carbon-carbon double bond to the polyimide precursor, and therefore the deterioration of resolution and large volume shrinkage at the time of curing cannot be avoided. On the other hand, a method has also been suggested in which a compound capable of generating an acid by light irradiation is utilized without using the compound having the carbon-carbon double bond to avoid such a problem. For example, the compound capable of generating the acid by light irradiation is blended with a polyimide having an acyloxy group in Japanese Patent Application Laid-open No. (Hei) 3-763, or with a polyamic acid derivative including an organic group introduced by an ester bond in Japanese Patent Application Laid-open No. (Hei) 4-120171, whereby the pattern treatment can be carried out. In the former, however, the volume shrinkage can be controlled, but the adhesive properties to substrates are poor. In the latter, the resolution is excellent, but the preparation of the polyamic acid derivative is inconveniently intricate.